Field of the Invention
The invention relates to an electric terminal, especially a terminal block comprising a terminal housing, at least two electrically conductive contact elements, at least two conductor connection elements for connecting electric conductors, and at least one separating element arranged movably in the terminal housing. In the first position of the separating element, the two contact elements are connected with each other, while in a second position of the separating element, the contact elements are separated from one another.
Description of Related Art
Electric terminals have been known for decades and are used by the millions in the wiring of electrical equipment and devices. The terminals are usually snapped onto a mounting rail which, in turn, is often arranged in a series (of mounting rails) in a control cabinet. Because they are arranged next to each other on a mounting rail or because they can be arranged in a series, the terminals are usually described as terminal blocks. Screw terminals, displacement connection terminals, or spring terminals (especially spring-cage terminals or, increasingly, leg spring terminal blocks as well) are often used as conductor connection elements in terminal blocks.
The basic type of terminal block is the connecting terminal which has at least two conductor connection elements that are electrically conductively connected with one another via an electrically conductive bus bar. In addition to this basic type (which is often called a feed-through terminal), there are a number of different types of terminal blocks which are specifically adapted for particular applications. These include, among others, the so-called disconnect terminals that, by means of mechanical separating elements, deliberately interrupt a signal circuit in order to, for example, make possible a measurement of the wiring in the field. When measuring ohmic resistances or insulation, measurement-, control-, and regulation signals could negatively influence the measurements.
In the state of the art, disconnect terminals are known in which the signal circuit can be interrupted by means of a so-called separating knife. The separating knife can thereby be pivoted in the terminal housing such that, in the first position of the separating knife, the two contact elements arranged fixedly in the terminal housing are connected with each other via the separating knife, while in a second position of the separating element, the contact elements are no longer electrically conductively connected to each other.
German Patent Application DE 10 2008 014 176 A1 and corresponding U.S. Pat. No. 8,581,131 disclose a terminal block in whose housing a pivotably mounted separating knife is arranged. To make the separating knife able to pivot inside of the terminal housing, the separating knife is arranged in an insulation housing in which a pivot is molded on one side wall. This pivot is mounted in an opening in a side wall of the terminal housing. In a first position, the separating knife thereby contacts the ends (which face each other) of the two sections of the bus bar, while in a second, pivoted position of the separating knife, the two sections of the bus bar are no longer connected with each other. As the ends (which face away from the separating knife) of the sections of the bus bar are connected with the conductor connection elements, the conductor connection elements are also no longer electrically connected with each other in the second position of the separating knife.
Furthermore, terminal blocks are known from practice that have a separating slide which is arranged to slide in the terminal housing in the direction of the longitudinal extension of the terminal block. These terminal blocks, too, have a bus bar comprising two sections. The ends of the bus bar face away from each other, and each end is connected to a conductor connection element. In a first position of the separating slide, the two ends of the sections (which are arranged opposite one another in the longitudinal direction) are electrically conductively connected with each other via the slide, while in a second position, the slide is only connected with one section, so that the two sections of the bus bar are not electrically conductively connected with each other. In the case of such terminal blocks (i.e., those which have a separating slide arranged to slide in the direction of the longitudinal extension of the terminal block), the distance between the two sections of the bus bar must be selected to be appropriately large enough to ensure a reliable signal separation. As a result, the installation space necessary for the separating mechanism in the direction of the longitudinal extension of the terminal block is relatively large.
In modern electronic systems, space requirements play an increasingly large role. The reduction in size of individual components which are simultaneously supposed to have a high functionality is therefore increasingly an important challenge. The possibility of reducing the dimensions of disconnect terminals is, however, limited by the fact that these terminals must have a large dielectric strength. Furthermore, a sufficiently large air gap/creepage distance must be ensured so that the signal separation can be securely realized. In the previously mentioned known disconnect terminals, a relatively large installation space is required (due to the pivoting or sliding of the separating knife) in order to ensure that the separating knife has, in the second position, a sufficient distance from the contact elements—that is, the ends of the bus bar sections.